Across desolate fields and shattered villages, Ukraine’s counteroffensive is confronting Russian minefields and Russian soldiers dug into elaborate trench networks.
But one unusually daunting obstacle to Ukrainian troops is a tactic adopted by Russian forces: ceding ground and then striking back.
Rather than holding a line of trenches at all costs in the face of Ukraine’s assault, security experts say, Russian commanders have employed a longstanding military tactic known as “elastic defense.”
To execute the tactic, Russian forces pull back to a second line of positions, encouraging Ukrainian troops to advance, and then strike back when the opposing forces are vulnerable — either while moving across open ground or as they arrive at the recently abandoned Russian positions.
The goal is to prevent Ukrainian troops from actually securing a position and using it as a base for further advances. That is what Ukraine was able to do successfully in the village of Robotyne in the south, its biggest breakthrough in recent weeks.
“The defender gives ground while inflicting as heavy casualties as they can on the attackers with a view to being able to set the attackers up for a decisive counterattack,” said Ben Barry, a senior fellow for land war studies at the International Institute for Strategic Studies, a British research group.
This tactic is just one of several factors that have impeded more rapid progress, according to Ukrainian officials and military experts. They also cite Moscow’s use of dense minefields, networks of trenches and tank barriers, and the reluctance of the country’s NATO allies to supply advanced fighter jets and longer-range weapons sooner in the war.
Perhaps the most formidable problem for Ukraine is Russia’s large stockpiles of artillery, which have been deployed throughout the conflict and not least to repel the counteroffensive that began in June.
Elastic defense is not a new strategy, Mr. Barry said. The Soviet Union employed it during its defeat of Germany in 1943 at the Battle of Kursk, one of the biggest on the eastern front during World War II. Russia also appears to have been applying it for some time in Ukraine, especially to hamper this summer’s counteroffensive.
“Historically it’s been used very successfully, but to succeed it requires good leadership and well-trained forces and to deliver decisive counterblows,” Mr. Barry said.
Assessing whether the tactic is being deployed on any given day is difficult without direct access to Russian commanders, experts said. But the Institute for the Study of War, an organization based in Washington, noted signs of it in recent days around the village of Robotyne, which fell to Ukrainian forces at the end of August.
Some significant field fortifications had changed hands several times, it said in a report this weekend, adding that Russian forces had “been conducting successful limited tactical counterattacks.”
Competing claims this week illustrated the issue: Russian forces said they had staged an assault on Ukrainian troops on the front line in the southern Zaporizhzhia region, where Kyiv has staged the main thrust of its counteroffensive, while Ukraine’s forces said they had “repelled the attacks.”
In a report on Monday, the institute said that geolocated footage and satellite imagery appeared to show that Ukraine had regained control of a trench system, southwest of Robotyne, that it had previously lost to Russian troops. Another indication of the back-and-forth nature of the fighting came on Tuesday, when Gen. Oleksandr Tarnavskyi, the head of Ukraine’s forces in the south, said that there had been an advance by his troops. It was not possible to verify his report.
In recent months, Ukraine’s war has consisted of battles for tiny villages and individual trench systems — contests that can last for weeks, with each side sustaining significant casualties to secure control. Overall, however, the conflict is being fought over a front line that stretches for hundreds of miles from the small city of Kupiansk, in the northeastern region of Kharkiv, where Russian forces have been trying to advance, to the Zaporizhzhia region in the south.
Ukrainian forces have also pushed forward in the south of an eastern region, Donetsk, where fighting over Bakhmut, one of the war’s most savage battles, has not stopped since Moscow gained control of the city in May.
President Volodymyr Zelensky of Ukraine visited troops near Kupiansk on Tuesday to hand out medals and inspect military equipment, including Leopard tanks that have been donated by the country’s NATO allies in Europe. His Telegram account posted a video of him in a forest shaking hands with a small group of soldiers, who appeared to include older men — a sign of the toll the war has taken on Ukraine.
Military experts believe that Russia, too, has suffered significant losses in the course of Ukraine’s counteroffensive, though it has slowed Ukraine’s military to a crawl, in part through its elastic defense.
A key factor in the successful implementation of the tactic is the judicious use of military reserves, who can be thrown into the battle for a counterattack, said Oleksiy Melnyk, a former Ukrainian commander who is now a senior official at the Razumkov Center, a nonprofit institute in the capital, Kyiv.
Moscow appeared to have begun to deploy elite airborne units to its defense in the Zaporizhzhia region, according to Mr. Melnyk, suggesting that its supply of regular reserves could be running thin — a development that Mr. Melnyk said would be “encouraging news” for Ukraine.
Michael Kofman, a senior fellow at the Carnegie Endowment for International Peace, said that if Moscow’s forces begin to retreat more than a few hundred yards at a time, and Ukrainian troops, particularly mechanized units, are able to build up enough momentum to advance in significant numbers, it would be a sign that Russia’s defensive strategy was beginning to falter.
“One of the biggest things that remains in question is whether or not the Ukrainian military will be able to achieve a breakthrough,” he said on the “War on the Rocks” podcast last week. One alternative, he said, is that “what we’re seeing is largely how this offensive was going to unfold from now until, let’s say, we get into the winter, or perhaps even through the winter.”